Spring integration: Send message from endpoint

In this post, I am going to explain following scenario.

a.   Producer send a message to consumer via ‘inputChannel’.

b.   Consumer reads the message from inputChannel and send acknowledgment to producer via outputChannel.

 

Find the below working application.

 

Step 1: Create new maven project ‘endpoint-reply-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>endpoint-reply-demo</artifactId>
	<version>1</version>

	<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-parent -->
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.4.0</version>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-integration</artifactId>
		</dependency>

	</dependencies>

</project>

 

Step 3: Create package 'com.sample.app.endpoints' and define ProducerEndpoint, ProducerAckEndpoint and ConsumerEndpoint classes.

 

ProducerEndpoint.java

package com.sample.app.endpoints;

import org.springframework.integration.annotation.Gateway;
import org.springframework.integration.annotation.MessagingGateway;
import org.springframework.stereotype.Component;

@Component
@MessagingGateway(name = "myGateway", defaultRequestChannel = "inputChannel")
public interface ProducerEndpoint {

	@Gateway(requestChannel = "inputChannel", replyTimeout = 2, requestTimeout = 200)
	public void produceMessage(String message);
	

}

 

ProducerAckEndpoint.java

package com.sample.app.endpoints;

import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.stereotype.Component;

@Component
public class ProducerAckEndpoint {

	@ServiceActivator(inputChannel = "ackChannel")
	public void receiveAcknowledgement(String message) {
		System.out.println("Received acknowledgement Consumer : " + message);
	}

}

ConsumerEndpoint.java

package com.sample.app.endpoints;

import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.messaging.Message;
import org.springframework.stereotype.Component;

@Component
public class ConsumerEndpoint {
	
	@ServiceActivator(inputChannel = "inputChannel", outputChannel = "ackChannel", requiresReply="true")
	public Message<String> consumeMessage(Message<String> message) {
		System.out.println("Received from Producer : " + message);
		return MessageBuilder.withPayload("Message Received").build();
	}
	


}

Step 4: Define App class in com.sample.app package.

 

App.java

package com.sample.app;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.integration.channel.DirectChannel;

import com.sample.app.endpoints.ProducerEndpoint;

@SpringBootApplication
@Configuration
public class App {

	@Autowired
	@Qualifier("inputChannel")
	private DirectChannel inputChannel;

	@Autowired
	@Qualifier("ackChannel")
	private DirectChannel ackChannel;

	public static void main(String[] args) {
		SpringApplication.run(App.class, args);
	}

	@Bean(name = "inputChannel")
	public DirectChannel channel1() {
		DirectChannel channel = new DirectChannel();
		return channel;
	}

	@Bean(name = "ackChannel")
	public DirectChannel channel2() {
		DirectChannel channel = new DirectChannel();
		return channel;
	}

	@Bean
	public CommandLineRunner demo(@Autowired ProducerEndpoint producerEndpoint) {
		return (args) -> {
			producerEndpoint.produceMessage("Hello World");

		};
	}

}

Total project structure looks like below.

 

Run App.java, you will see below messages in console.

 

Received from Producer : GenericMessage [payload=Hello World, headers={replyChannel=nullChannel, id=842f54f2-54d1-93a8-619b-a6ef3548e6db, timestamp=1617373206585}]

Received acknowledgement Consumer : Message Received

 

You can download complete working application from below link.

https://github.com/harikrishna553/springboot/tree/master/spring-integration/endpoint-reply-demo

 

 

 

 

 

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